Background: No previous population-based studies have examined secular trends in the incidence of intracerebral hemorrhage (ICH) by its location.
Methods and results: We established 3 cohorts consisting of residents of Hisayama, Japan, aged ≥40 years without a history of stroke or myocardial infarction in 1961 (the first cohort, n=1,618), in 1974 (the second cohort, n=2,038), and in 1988 (the third cohort, n=2,637). Each cohort was followed for 13 years. The age- and sex-adjusted incidence of ICH significantly declined from the first to the second cohort and showed no further change in the third cohort. With regard to the ICH location, the incidence of putaminal hemorrhage decreased steadily, mainly in subjects aged 60-69 years, whereas the incidence of thalamic hemorrhage increased, especially in those aged ≥70 years. Both hypertension and alcohol intake were strong risk factors for ICH in the first cohort, but their influence declined with time. Blood pressure levels in hypertensive subjects decreased significantly, and the proportion of current drinkers decreased slightly over the study period.
Conclusions: Our findings suggest that the ICH incidence steeply declined from the 1960s to the 1970s in Japan as a result of the reduced influence of hypertension and alcohol intake, but that this decline has leveled off since then, probably because of the increased incidence of thalamic hemorrhage in the elderly in recent years.